"In Italy, there's the feeling that Vidal may be the marquee player to leave Juventus during this transfer window.

"After the shock of Conte's departure, Juventus have pushed ahead with a move for Argentinean Roberto Pereyra from Udinese, who could be seen as a reasonable replacement for Vidal in a starting XI that new coach Massimiliano Allegri will switch from 3-5-2 to 4-3-1-2."

United have monitored the situation regarding Vidal closely during a turbulent summer at Juventus, which has seen Antonio Conte leave the Serie A champions amid talk of unhappiness regarding the club's transfer policy.

Juventus have signed forward Alvaro Morata from Real Madrid and are set to complete a move for Roberto Pereyra, while suggestions that Vidal could be sold grow louder in Italy.

Vidal, who is currently resting in Chile following the World Cup, has recently conceded that his future in Turin looks uncertain.

"I don't feel like my time at Juventus is over, although I can't say more right now," he told a Chilean radio station. "When I'm back from Chile, I'll talk to my executives and we'll see what will happen."

Juve director Pavel Nedved, meanwhile, says that the club are reluctant to sell both Vidal and Paul Pogba but admits that a big-money bid could force them to part ways with the Chilean.

"Our strategy is clear; we want to keep all our best players, including Vidal and Pogba," he told Tuttosport. "We don't want to sell anyone, especially Vidal.

"Certainly, if there were a high bid for them, we'd have to think about it but we don't want to sell our champions.

"We want to be competitive in the Champions League and the only sales to be players who are not part of our plans."

Publicly, United have aimed to manage expectations regarding signings but Vidal has emerged as their No.1 target and chief executive Ed Wooward has confirmed that the club are still in the market for players this summer.

"We've been working with Louis over several weeks with regards to targets and we're continuing to move forward on some of those targets," Woodward told MUTV.

He added: "We are willing to invest. There is no fixed budget. Financially we are extremely strong and funds are available. Louis is assessing what's going on and there is a lot of work going on behind the scenes, so watch this space."